Low-density microcellular foam and method of making same

Abstract

Low-density microcellular foam having a cell size of not greater than 2 mu m and method of making by dissolving cellulose acetate in an acetone-based solvent, gelling the solution in a water bath maintained at 0 DEG -10 DEG C for a selected period of time to allow impurities to diffuse out, freezing the gel, and then freeze-drying wherein water and solvents sublime and the gel structure solidifies into low-density microcellular foam. The foam has a density of 0.065 to 0.6x103 kg/m3 and cell size of about 0.3 to 2 mu m. The small cell size foam is particularly applicable for encapsulation of laser targets.

What I claim is: 
     
       1. A cellulose acetate foam having a density in the range of 0.065 to 0.6×10 3  kg/m 3  and a cell size in the range of 0.3 to 2 μm. 
     
     
       2. The foam defined in claim 1, wherein the density is about 0.1×10 3  kg/m 3  and the cell size is about 2 μm.